Question: In history class, the girl to boy ratio is $10$ to $2$. If there are a total of $24$ students, how many boys are there?
A ratio of $10$ girls to $2$ boys means that a set of $12$ students will have $10$ girls and $2$ boys. A class of $24$ students has $2$ sets of $12$ students. Because we know that there are $2$ boys in each set of $12$ students, the class must have $2$ groups of $2$ boys each. There is a total of $4$ boys in history class.